But she not only conquered it — she’s been chugging at full throttle ever since, first with last year’s knockout followup, “Kaleidoscope Heart,” which debuted at No. 1, then spun out quirky smash hits like “King of Anything,” “Uncharted” and “Gonna Get Over You.”

Also new are the iTunes single “Love Is Christmas,” a duet with Seth MacFarlane on his debut recording “Music Is Better Than Words” and an EP she is tracking in Nashville.

“I don’t have a name for it quite yet, but I think we’re looking at five or six songs, and there’s one that has a lot of bad words in it,” says Bareilles of the early-2012 release, which she may preview in concert Saturday in San Francisco.

“Things ebb and flow for me, but coming to Nashville for this EP was definitively a creative little spurt — I felt really in touch with the source, and I’m kind of tapping into some really cool stuff. So it’s been nice to get back to a place where I felt really inspired again.”

Bareilles, 32, used the Nashville sessions to experiment, building her studio songs up from bare-bones home demos. “Which I’ve never done before, so I’m coming at it from a totally different process,” she says.

Her producer is fellow pianist Ben Folds, whom she befriended on NBC’s “The Sing-Off,” where they — along with Boyz II Men’s Shawn Stockman — were this third season’s celebrity judges.

“Sing-Off” producers were so impressed by Bareilles’ appearance on their season two finale that they hired her full-time.

But judging the a cappella contestants hasn’t been easy, she says. She wound up getting attached to certain performers, but ultimately weighing their potential against recording-industry realities. “Sometimes dealing with the aftermath of an audience reaction is not pleasant,” she says. “They get angry.”

Visually, Bareilles is also hitting inventive new heights. Her clever clip for “Uncharted” features rock star chums like Adam Levine, Ryan Tedder and Josh Groban lip-synching the lyrics, and in “Gonna Get Over You” — directed by her longtime bud Jonah Hill — she performs a “Grease”-campy dance number with neighborhood extras in an East L.A. bodega.

“Jonah wanted to get into music videos, and I fully supported him. I said ‘I’ll be your guinea pig!’” she says. “And I love dancing, but I’m not a dancer. So I had a blast — and some bruises.” IF YOU GO